1. Field of the Invention
The present invention relates to a planetary gear type transmission system for seven forward speeds and one rearward speed (making use of multiple clutch discs of wet type) that is available in a dump truck or the like.
2. Description of the Prior Art
Heretofore, as a planetary gear type transmission system for use in a middle-size dump truck, that for six forward speeds and one rearward speed as shown in FIG. 7 has been known. However, in recent years, it has become obvious that as a planetary gear type transmission system of such class, a transmission system for seven forward speeds and one rearward speed is most suitable in a ramp climbing property, an accelerating property and the like.